1. Field of the Invention
The invention broadly concerns methods for conducting PCR-based assays useful in the detection of LGV-causing serotypes of Chlamydia trachomatis. More specifically, in this invention, an assay of a sample utilizes a first primer having a nucleotide sequence flanking one side of a deletion of the cytotoxin gene locus, and a second primer having a nucleotide sequence flanking the other side of this deletion, wherein synthesis of a sequence-specific amplicon containing the point of the deletion indicates that the sample contains nucleic acid specific to an LGV-causing serotype of Chlamydia trachomatis. 
2. Description of the Related Art
Chlamydia trachomatis is an obligate intracellular prokaryote. This organism includes the A, B, C, D, E, F, G, H, I, G, K, L I, L II, and L III serotypes (Carlson et al., 2004, Polymorphisms in the Chlamydia trachomatis cytotoxin locus associated with ocular and genital isolates. Infection and Immunity 72:7063-7072). Serotypes of the L group of Chlamydia trachomatis (e.g., the L I, L II, and L III serotypes) are the causative agents of LGV. This disease, which is sexually transmitted, is characterized by three stages. In the primary stage, small, painless herpetiform genital ulcers are formed which are often not recognized and resolve spontaneously. The secondary stage presents itself as lymphadenopathy usually without any genital lesions. The tertiary stage, also known as the anorectal/elephantiasis stage, is typified by permanent disfigurement resulting from destroyed inguinal lymphoid tissue (Sturm et al., 2005, Molecular diagnosis of lymphogranuloma venereum in patients with genital ulcer disease. Journal of Clinical Microbiology 43:29732975). Thus, a need exists to quickly identify infection of a subject by a serotype of Chlamydia trachomatis belonging to the L group so that a medical practitioner can intervene and administer the appropriate treatment to prevent the onset of or ameliorate the destructive tertiary stage of LGV.